A55 motors are paired with delorto PHVA carb and they have different cylinder+head cooling fins.
Since you mentioned sha carb, I took a closer look and that is a varient of the tomos A35 or A5 motor.
So its a fine example of a tomos that needed, what treatland refered to as, a "revival pipe". A35 header angle with A55 chassis rear mount. (edited)